The objective of this project is to study the induction and effect of DNA variance in male offspring of mice treated with known mutagens and in certain inbred homozygous mouse strains. Some genetic events such as translocations cause abnormal sperm DNA content but there are other events in spermatogenesis that may also result in sperm with abnormal amounts of DNA. The Axiomat scanning microscope is being used to quantitate the DNA fluorescence of single sperm and spermatids. The measured distributions of DNA fluorescence are being evaluated within and between normal mice, those with known translocations, offspring of treated mice, and inbred strains with a proportion of spermatids that undergo total or partial nuclear non-disjunction during spermatogenesis.